Electrochemical device with adjustable-area electrodes using a hydrogen peroxide catholyte

• US 20040028989A1
• Filed: 12/10/2002
• Published: 02/12/2004
• Est. Priority Date: 12/11/2001
• Status: Abandoned Application

• Current Assignee: Powerzyme
• Original Assignee: Powerzyme
• Inventors: Sun, Hoi-Cheong Steve, Tian, Yongchi, Lipp, Steven Alan, Whipple, Richard T.
• Application Number:
  US10/315,531
• Publication Number:
  US 20040028989A1
• Time in Patent Office: Days
• US Class Current: 429/40
• CPC Class Codes: H01M 4/8605 Porous electrodes
• CPC Class Codes: H01M 4/9008 Organic or organo-metallic compounds
• CPC Class Codes: H01M 8/0289 Means for holding the electrolyte solid polymer electrolytes H01M8/1018
• CPC Class Codes: H01M 8/04582 of the individual fuel cell
• CPC Class Codes: H01M 8/0494 of fuel cell stacks
• CPC Class Codes: H01M 8/08 Fuel cells with aqueous electrolytes
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

Provided is an electrochemical device having an electron source and a hydrogen peroxide solution for reaction to accept the electrons, the device with an anode compartment and a cathode compartment, including (a) a cathode electrode having an area, which can be adjustable, in contact with the cathode compartment of A_C; and (b) an anode electrode having an area, which can be adjustable, in contact with the anode compartment of A_A, wherein either the cathode or anode electrode area or both are adjustable, such that A_C/A_A=EAR is adjustable, and wherein, where j_EC is the anode current provided by the electron carrier, and j_TOS is a diffusion-limited current density for a reaction by oxygen in an oxygen saturated said hydrogen peroxide solution, EAR is selected such that either

(a) EAR≦j_EC/j_OS, or

(b) j_EC/EAR approaches the value of j_TOS.

Claims

1. A fuel cell comprising:

an anode compartment, a cathode compartment, a membrane disposed between said anode and said cathode compartments said membrane being capable of passing positive charge from said anode compartment to said cathode compartment, an anode disposed within said anode compartment having an anode surface area A_A, a cathode disposed within said cathode compartment having a cathode surface area A_C, wherein A_A is in electrical communication with A_C and there being an electrode area ratio (EAR) equal to A_C/A_A, an electron source for providing electrons disposed within said anode compartment in electrical communication with said anode and an aqueous peroxide catholyte solution in said cathode compartment in contact with A_C, wherein the A_C and A_A are selected such that EAR≦

J_EC/J_TOS, where J_EC is the anode electron current provided by said electron source and J_TOS is the diffusion limited electron current density for oxygen in said peroxide catholyte solution saturated with oxygen.

2. The fuel cell according to claim 1, wherein at least one of A_A or A_C is adjustable.

3. The fuel cell according to claim 1, wherein the EAR is selected such that

J_EC/EAR approaches J_TOS.

4. The fuel cell according to claim 1, wherein the A_C and A_A are selected so that the maximum available current density due to electron consumption by reaction of peroxide (J_PM) is given by the relation

j_PM≧

j_EC/EAR≧

10*j_TOS

5. The fuel cell according to claim 4, wherein the A_C and A_A are selected so that the maximum available current density due to electron consumption by reaction of hydrogen peroxide (J_PM) is given by the relation

j_PM≧

j_EC/EAR≧

20*j_TOS.

6. The fuel cell according to claim 5, wherein the A_C and A_A are selected so that the maximum available current density due to electron consumption by reaction of hydrogen peroxide (J_PM) is given by the relation

j_PM≧

j_EC/(A_C/A_A)≧

30*j_TOS.

7. The fuel cell according to claim 1, wherein said peroxide is hydrogen peroxide.

8. The fuel cell according to claim 1, further comprising:

one or more detectors for detecting one or more operating parameters of the electrochemical device; and

one or more adjusters to receive said one or more operating parameters from said one or more detectors and respond to adjust the EAR by changing at least one of A_C or A_A.

9. The fuel cell according to claim 8, wherein said adjuster is a controller adapted to electronically communicate to said fuel cell.

10. The fuel cell according to claim 8, wherein said controller is connected to a communications network.

11. The fuel cell according to claim 1, wherein EAR≦

2.5.

12. The fuel cell according to claim 1, wherein EAR≦

2.0.

13. The fuel cell according to claim 1, wherein EAR≦

1.5.

14. A fuel cell comprising:

an anode compartment, a cathode compartment, a membrane disposed between said anode and said cathode compartments said membrane being capable of passing positive charge from said anode compartment to said cathode compartment, an anode disposed within said anode compartment having an anode surface area A_A, a cathode disposed within said cathode compartment having a cathode surface area A_C, wherein A_A is in electrical communication with A_C and there being an electrode area ratio (EAR) equal to A_C/A_A and wherein EAR≦

2.5, an electron source for providing electrons disposed within said anode compartment in electrical communication with said anode and an aqueous peroxide catholyte solution in said cathode compartment in contact with A_C.

15. The fuel cell according to claim 14, wherein EAR≦

2.0.

16. The fuel cell according to claim 14, wherein EAR≦

1.5.

17. The fuel cell according to claim 14, wherein the voltage or current obtained is greater than the amount which could be obtained from oxygen in an oxygen saturated peroxide catholyte solution.

18. The fuel cell according to claims 14, wherein said catholyte includes hydrogen peroxide and oxygen and wherein said EAR is selected such that the maximum available current density due to electron consumption by reaction of hydrogen peroxide (J_PM) is ≧

10*j_TOS where j_TOS is the diffusion limited electron current density for oxygen in a peroxide catholyte solution saturated with oxygen.

19. The fuel cell according to claim 18, wherein said catholyte includes hydrogen peroxide and oxygen and wherein said EAR is selected such that the maximum available current density due to electron consumption by reaction of hydrogen peroxide

(J_PM) is ≧

20*j_TOS where j_TOS is the diffusion limited electron current density for oxygen in a peroxide catholyte solution saturated with oxygen.

20. The fuel cell according to claim 19, wherein said catholyte includes hydrogen peroxide and oxygen and wherein said EAR is selected such that the maximum available current density due to electron consumption by reaction of hydrogen peroxide

(J_PM) is ≧

30*j_TOS where j_TOS is the diffusion limited electron current density for oxygen in a peroxide catholyte solution saturated with oxygen.

21. The fuel cell of claim 14, wherein said peroxide is hydrogen peroxide.

22. The fuel cell according to claim 14, further comprising:

one or more detectors for detecting one or more operating parameters of the electrochemical device; and

one or more adjusters to receive said one or more operating parameters from said one or more detectors and respond to adjust the EAR by changing at least one of A_Cor A_A.

23. The fuel cell according to claim 22, wherein said adjuster is a controller adapted to electronically communicate to said fuel cell.

24. The fuel cell according to claim 23, wherein said controller is connected to a communications network.

25. The fuel cell according to claim 14 wherein at least one of A_A or A_C is adjustable to provide a desired EAR.

26. A method of adjusting electrical current flow by varying a surface area of one or more electrodes of a fuel cell comprising:

an anode compartment, a cathode compartment, a membrane disposed between said anode and said cathode compartments said membrane being capable of passing positive charge from said anode compartment to said cathode compartment, an anode disposed within said anode compartment having an anode surface area A_A, a cathode disposed within said cathode compartment having a cathode surface area A_C, wherein A_A is in electrical communication with A_C and there being an electrode area ratio (EAR) equal to A_C/A_A, an electron source for providing electrons disposed within said anode compartment in electrical communication with said anode and an aqueous peroxide catholyte solution in said cathode compartment in contact with A_C, the method comprising

changing the EAR by selectively connecting said anode and said cathode electrodes, thereby affecting current flow.

27. The method according to claim 26, wherein the electron acceptor is a hydrogen peroxide solution.

28. The method according to claim 27, further comprising

adjusting EAR such that, where j_EC is the anode current provided by the electron source, and j_TOS is a diffusion limited current density for a reaction by oxygen in an oxygen saturated hydrogen peroxide solution used as the electron acceptor

EAR≦

j_EC/j_TOS.

29. The method according to claim 27, further comprising

adjusting EAR such that, where j_EC is the anode current provided by the electron source, and j_TOS is a diffusion limited current density for a reaction by oxygen in an oxygen saturated hydrogen peroxide solution used as the electron acceptor

j_EC/EAR approaches j_TOS.

30. The method according to claim 26, further comprising

monitoring one or more operating parameters of the electrochemical device;

and

changing the EAR in response to the monitored operating parameters.